Method and apparatus for the clearing of minefields

ABSTRACT

Clearance of a minefield is effected using first and second ground-engaging drive units ( 63  and  64 ), each of which includes a milling or grinding drum ( 6 ). The first drive unit ( 63 ) is connected to the front of a multi-purpose vehicle or tractor ( 62 ) and the second drive unit ( 64 ) is connected to the rear of the vehicle or tractor ( 62 ) to form a mine clearance apparatus which can be driven over the land to be cleared of mines with the vehicle or tractor ( 62 ) supported clear of the ground by the first and second drive units ( 63  and  64 ). The milling or grinding drum ( 6 ) of the first drive unit ( 63 ) grinds up the surface vegetation and the milling or grinding drum ( 6 ) of the second drive unit ( 64 ) grinds up a layer of soil and any anti-personnel mines contained therein.

FIELD OF THE INVENTION

[0001] This invention relates to a method and apparatus for the clearingof minefields, and is particularly concerned with the clearance ofburied anti-personnel mines.

[0002] Current methods for the clearance of minefields, particularlyafter the minefields have been laid for a number of years, involve anumber of time-consuming operations. In particular, it is necessary toclear any vegetation which has grown since the minefield was laid priorto the removal or destruction of the land mines using explosive charges.The mines are located only after careful removal of the vegetation,followed by probing of the soil with mine probes.

[0003] It is a particular disadvantage of the conventional clearancemethods that probing using probes and destruction using explosivecharges often result in additional safety hazards for the personnelcarrying out the mine clearance operation.

[0004] Another disadvantage of the conventional methods is that chemicalpollution arising from extensive use of explosives can producedegradation of the agricultural properties of the soil to such an extentthat the land which has been cleared is not suitable for agriculturaluse for many years.

[0005] It is accordingly an object of the present invention to providean improved method for the clearance of anti-personnel mines andimproved apparatus for the carrying out of said method.

SUMMARY OF THE INVENTION

[0006] According to a first aspect of the present invention there isprovided a method for the clearance of anti-personnel mines, the methodcomprising:

[0007] a) providing a first ground-engaging drive unit which includes amilling or grinding drum,

[0008] b) providing a second ground-engaging drive unit which includes amilling or grinding drum,

[0009] c) connecting the first drive unit to the front of a vehicle andthe second drive unit to the rear of the vehicle to form a mineclearance apparatus, and

[0010] e) driving the mine clearance apparatus over the land to becleared in such manner that the milling or grinding drum of the firstdrive unit grinds up the surface vegetation and the milling or grindingdrum of the second drive unit grinds up a layer of soil and anyantipersonnel mines contained therein.

[0011] According to a second aspect of the present invention there isprovided apparatus for use in the clearance of a minefield, theapparatus comprising first and second ground-engaging drive units eachof which includes a milling or grinding drum, and each drive unit beingprovided with connector means such that the first drive unit can beconnected to the front of a vehicle and the second drive unit can beconnected to the rear of the vehicle to form an apparatus which can bedriven over the land to be cleared in such manner that the milling orgrinding drum of the first drive unit grinds up the surface vegetationand the milling or grinding drum of the second drive unit grinds up alayer of soil and any anti-personnel mines contained therein.

[0012] The vehicle is preferably connected to the first and second driveunits in such manner that, when the apparatus is being driven over theland to be cleared of mines, the vehicle is supported clear of theground by said first and second drive units.

[0013] The first drive unit preferably includes a detector for thedetection of buried objects larger than anti-personnel mines.

[0014] The first drive unit preferably includes blockage preventionmeans to prevent clogging of the milling or grinding drum due toexcessive vegetation, wet soil or other adverse conditions.

[0015] The first and second drive units preferably each include a blastdamage reduction device to obviate damage due to blast energy fromexploding anti-personnel mines.

[0016] The second drive unit preferably includes a soil filtering devicefor preparing the de-mined soil for agricultural seeding.

[0017] An integrated drive and governor system is preferably providedfor moving the apparatus over the ground to be cleared under the powerof the prime mover of the vehicle.

[0018] An integrated steering and fixing system is preferably alsoprovided.

[0019] Means are preferably provided on the first drive unit forprojecting ground-up vegetation upwardly and rearwardly so that it isapplied on top of ground-up soil discharged from the second drive unit.

[0020] The first and second drive units preferably include many commoncomponents to facilitate repair and maintenance.

[0021] Thus, according to a third aspect of the present invention thereis provided a drive unit which includes a milling or grinding drum,connector means for connection of the drive unit to the front or rear ofa vehicle so that, when driven over the land to be cleared the millingor grinding drum grinds up either the surface vegetation or a layer ofsoil and any anti-personnel mines contained therein, and a blast damagereduction device to obviate damage due to blast energy from explodinganti-personnel mines.

BRIEF DESCRIPTION ON THE DRAWINGS

[0022]FIG. 1 is a perspective view of a drive unit with cut-out sectionsshowing component parts of the drive unit,

[0023]FIG. 2 is a cross-sectional view of the forward-looking detector,with ground-speed radar and processing electronics,

[0024]FIG. 3 is a sectional view of a front drive unit,

[0025]FIG. 4 is a sectional view of the milling or grinding drum usedfor lifting and destroying buried land mines or vegetation,

[0026]FIG. 5 shows a blockage prevention device and a blast damagereduction device,

[0027]FIG. 6 shows a soil filtering system,

[0028]FIG. 7 is a sectional side view of the integrated steering andfixing system of the mine clearance apparatus,

[0029]FIG. 8 is a plan view of the integrated steering and fixing systemlooking from the base to the top,

[0030]FIG. 9 is an overview of the integrated drive and governor systemof the apparatus, and

[0031]FIG. 10 shows a particular application of the apparatus being usedto remove vegetation and clear anti-personnel mines.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0032] The drive unit shown in FIG. 1 is intended to form part of anapparatus, as shown in FIG. 10, for clearing vegetation andanti-personnel mines. The drive unit includes a main frame consisting ofleft and right side covers 1 and 2 joined by a central box-section beam3. The frame houses two driving rollers 4 and 5 located at the front andthe rear of the frame and a milling or grinding drum 6 located at themid-point of the frame, directly below the central beam 3. A pluralityof tungsten carbide teeth 7 are attached to the milling or grinding drum6. The milling or grinding drum 6 is arranged so that, as viewed in FIG.1, it rotates in a clockwise direction.

[0033] A multi-sectioned shear bar 8 is fixed to the central box-sectionbeam 3 above the milling or grinding drum 6. An integrated steering andfixing device 9 is also attached to the central box-section beam 3.

[0034] In FIG. 1, the front drive roller 4 is shown cut away toillustrate the location and mounting of a forward looking detector 10which is held in the centre of the roller 4 on a fixed shaft 11.

[0035] A blast shield 12 is located above and to the left of the millingor grinding drum 6. The shield 12 is used to dissipate energy from anyoccurrence of detonation during the lifting and destruction ofanti-personnel mines. The blast shield 12 is operated upon by thecombination of two springs 13 (only one of which can be seen in FIG. 1)attached to the left and right side covers 1 and 2, and a side crankmechanism 14. The blast shield 12 is held above and to the left of themilling or grinding drum 6 by four solid straps 15 mounted on the leftand right side covers 1 and 2.

[0036]FIG. 1 also shows the location of a soil filtering system 16. Theside cover 2 is shown cut away to illustrate the soil filtering system16 attached to the central box-section beam 3 directly behind themilling or grinding drum 6.

[0037]FIG. 1 also shows the location of two hydraulic motors 17 and 18which are used to drive the front and rear drive rollers 4 and 5. Twoother hydraulic motors 19 (only one of which can be seen in FIG. 1) areused to drive the milling or grinding drum 6. Independent drive systemsare thus provided for the two drive rollers 4 and 5 and for the drum 6.

[0038] As shown in FIG. 2, the forward-looking detector 10 is connectedto the fixed shaft 11 by a fixing support 20. A ground speed radarsystem comprising a transmitting device 21 and a receiving device 22 ismounted on the forward-looking detector 10. The radar system 21, 22 isused to send ground travel speed information to a global positioningdevice and computer 26 on board a multi-purpose vehicle or tractor 62(see FIG. 10). An electronic unit 25 is mounted on the fixing support 20and a key-way 23 is cut into the fixed shaft 11 to receive theelectrical cables 24 interconnecting the electronic unit 25 and theglobal positioning device and computer 26.

[0039] As shown in FIG. 3, the fixed shaft 11, on which the forwardlooking detector 10 is mounted, is contained within the front roller 4.The shaft 11 is attached by means of a fixing plate 27 to the side cover1 and carries a bearing 28 on which the front drive roller 4 is mounted.This arrangement allows the hollow front drive roller 4 to rotate whilethe shaft 11 remains fixed relative to the side cover 1 The end of thefixed shaft 11 remote from the side cover 1 is connected to a secondshaft 30 by a spigot coupling 29. The second shaft 30 is supported bymeans of a bearing 68 mounted on the side cover 2. The second shaft 30is fixed to the front drive roller 4 and to the output element of thefront hydraulic motor 17. The front hydraulic motor 17 thus rotates thesecond shaft 30 and the front drive roller 4, while the fixed shaft 11remains stationary.

[0040]FIG. 4 shows one end of the milling or grinding drum 6 which, inthe case of a front drive unit, is used to mulch vegetation or soil and,in the case of a rear drive unit, to grind up any anti-personnel mineswhich are encountered. There is a hydraulic motor 19 at each end of thedrum 6 and the hydraulic power to the two motors 19 is supplied by themulti-purpose vehicle or tractor 62. The output element of eachhydraulic motor 19 is connected to a respective shaft 31 fixed to themilling or grinding drum 6 by means of a fixing plate 34. A plurality ofhigh-speed tungsten carbide tips 7 are carried by the milling orgrinding drum 6 and the arrangement is such that, as the drum 6 isrotated, all the materials which are encountered, e.g. the soil,vegetation and mines, are ground up as they are forced past the shearbar 8 by the tungsten carbide tips 7 All the soil and vegetation isconverted into mulch and the mines are ground into pieces or detonated.

[0041]FIG. 4 also shows part of the crank and slider mechanism 14, theblast shield 12 and a bearing 32 which is carried by the left coverplate 1 and supports one end of the shaft 31.

[0042]FIG. 5 illustrates the mode of operation of the blockageprevention system which acts as an automatic governor for the milling orgrinding process. It includes the blast shield 12 which is supportedfrom the left and right side covers 1 and 2 by four solid pivotedstraps. Two of the straps, i.e. straps 15 and 35, are shown in FIG. 5.Counter-torque on the hydraulic motor 19, caused by an increase in thevolume of soil or vegetation being mulched, or by a blast from ananti-personnel mine, will cause the crank and slider mechanism 14 tomove and lift the blast shield 12 away from the milling or grinding drum6. This movement is in a direction at right angles to the surface of thedrum 6. Movement of the blast shield 12 is detected by a position sensor36 located on the slider component of the crank and slider mechanism 14.The output of the position sensor 36 is used to reduce the hydraulicpower inputs to the hydraulic motors 17 and 18 which drive the front andrear drive rollers 4 and 5. The resulting reduction in forward speed andlifting of the blast shield 12 alleviates clogging and the effects ofblast damage.

[0043]FIG. 6 shows the soil filtering system 16. The system 16 includesa number of spring filter rods 37 only one of which is shown in FIG. 6.The other rods 37 are arranged in parallel relationship with the rod 37shown in FIG. 6. The rods 37 are secured to a plate which has a hinge 38which can move through pre-set parameters. When the machine is inoperation, the soil filter rods 37 are able to move altogether on thehinge 38 and individually (because of the spring characteristics). Therods 37 thus act to filter the material being forced out through the gapbetween the teeth 7 on the drum 6 and the shear bar 8. The action ofeach individual rod 37 and the change in angle of the hinge unit, movingall the rods 37 through the same angle, is automatic, depending on thequantity and condition of the soil being ground in the milling orgrinding process. As the soil is passed through the gaps between thefilter rods 37, the soil is separated and sieved preparing the soil sothat it is ready for agricultural seeding.

[0044]FIGS. 7 and 8 show the integrated steering and fixing system 9which allows the device to be fixed and controlled hydraulically byeither a multi-purpose vehicle or tractor 62. The steering and fixingsystem allows controlled hydraulic movement in all three axes, i.e.steering left and right movements, crowd and tilt and roll back andforth. The steering system includes a swivel ball joint 39 which isattached to two plates 40 and 41 which have standard three-point linkagecoupling connections 42 and 43. These coupling connections 42 and 43provide the connections to the multi-purpose vehicle or tractor 62. Theleft side plate 40 has a single coupling lobe, while the right sideplate 41 has double coupling lobes 42 to allow connection to either thefront or back of the multi-purpose vehicle or tractor 62. Four hydraulicrams 44, 45, 47 and 48 act between the side plates 40 and 41, two of therams 44 and 45 being shown in FIG. 7. The hydraulic rams 44, 45, 47 and48 are held by eight flexible couplings, one of which is indicated as 46in FIG. 7.

[0045] The underside of the integrated steering and fixing system isshown in FIG. 8 and the arrangement is such that steering movement tothe right and left is controlled by hydraulic rams 44 and 47. Reducingthe effective length of the piston of hydraulic ram 44 and increasingthe length of the piston of hydraulic ram 47 will cause plate 40 toangle in one direction. Reversing the operation of the two hydraulicrams 44 and 47 will cause plate 40 to angle in the opposite direction.

[0046] Crowd and tilt movement can be effected by movement of a furtherhydraulic ram 67 (see FIG. 9). By reducing the effective length of ram67, the front of the machine is pulled up towards plate 41. This canforce the machine up onto the rear roller 5, thereby lifting the millingor grinding drum 6 up out of the ground. Similarly, reversing thisoperation will tilt the machine in the opposite direction, eventuallyforcing it up onto the front roller 4.

[0047] Changing the effective lengths of hydraulic rams 45 and 48 willcause plate 40 to roll back and forth relative to plate 41.

[0048]FIG. 9 shows the operation of the integrated drive and governorsystem which includes two external hydraulic pumps 49 and 50. The powerfor the pumps 49 and 50 is supplied by the engine 51 of themulti-purpose vehicle or tractor 62. The power for hydraulic motors 17and 18 (which are used to turn the front and rear drive rollers 4 and 5)is derived from the hydraulic power generated by pump 49 via a flowdivider valve 52. The flow divider valve 52 operates to split the singlehydraulic input into a double output, the two parts of which have equalvolume of hydraulic oil flow. The output of pump 49 is fed to the driverollers 4 and 5 via three flow control valves 53, 54 and 55 interposedbetween the flow divider valve 52 and the hydraulic pump 49. Thehydraulic pump 49 can also be used to power a second apparatus (notshown) connected to one of the outputs of a flow divider valve 56interposed between flow control valves 53 and 54.

[0049] The flow control valves 53, 54 and 55 operate to govern thehydraulic power supplied to the motors 17 and 18 and hence the speed ofthe motors 17 and 18. Operation of the first control valve 53 is in turncontrolled by the positioning sensor 36 located on the slider of theslider crank mechanism 14. When a build-up of material or a blast causesthe slider mechanism 14 to operate, the sensor 36 sends a signal to thesolenoid of the flow control valve 53, thus reducing the power suppliedto the hydraulic motors 17 and 18.

[0050] The next flow control valve 54 is used to prevent the engine 51of the multi-purpose vehicle or tractor 62 from becoming over-loaded.This valve 54 is operated from a “revs. per minute” signal output fromthe engine 51. The third flow control valve 55 is operated by anexternal control device joystick 57 located in the multi-purpose vehicleor tractor 62. This allows the driver of the multi-purpose vehicle ortractor 62 to control the forward speed of the two drive rollers 4 and5.

[0051] The hydraulic pump 50 is used to provide power to the twohydraulic pumps 19 which drive the milling or grinding drum 6 of eachdrive unit. The supply of hydraulic oil to the motors 19 is fed througha flow divider valve 58 allowing the pump 50 to be connected to a secondapparatus (not shown).

[0052] Joystick 57 also controls the operation of the integratedsteering and fixing system by sending signals to a solenoid box 59 whichis used to control the hydraulic rams 44, 45, 47, 48 and 67. Thesolenoid box 59 has a second connection allowing control of a secondintegrated steering and fixing system, i.e. of a second deminingapparatus being operated in parallel with the apparatus attached to themulti-purpose vehicle or tractor 62.

[0053] The integrated steering and fixing system also includes anexternal solid state gyroscope 60 which is connected to an electronicsignal interface box 61 which is used to operate the solenoid box 59.This allows automatic accurate control of the position of the land mineclearance apparatus in relation to the position of the multi-purposevehicle or tractor 62.

[0054]FIG. 10 shows the apparatus being used to clear vegetation andanti-personnel mines simultaneously. Two substantially identical driveunits 63 and 64 are used, one mounted on the front of the multi-purposevehicle or tractor 62 and the other mounted on the rear thereof The twodrive units 63 and 64 are connected to the multi-purpose vehicle ortractor 62 via the integrated steering and fixing systems 9 describedabove and the front and rear hydraulic connections on the multi-purposevehicle or tractor 62 are used to operate the hydraulic rams 44, 45, 47,48 and 67 of the integrated steering and fixing systems 9. Themulti-purpose vehicle or tractor 62 can be elevated (as shown in FIG.10) and supported between the front and rear or first and second driveunits 63 and 64 by operation of the hydraulic three-point linkagecouplings located on the front and rear of the multi-purpose vehicle ortractor 62.

[0055] The axial position of the multi-purpose vehicle or tractor 62relative to the ground is controlled by a reference signal from theelectronic signal interface box 61 mounted on the multi-purpose vehicleor tractor 62. The signal interface box processes the reference signalfrom the solid state gyroscope 60, which is also mounted on themulti-purpose vehicle or tractor 62.

[0056] The front drive unit 63 can be angled with reference to theground such that the milling or grinding drum 6 of the front drive unit63 is positioned slightly above the ground and the rear drive roller 5of the front drive unit 63 is the only part of the front drive unit 63to be in contact with the ground.

[0057] The milling or grinding drum 6 of the rear drive unit 64 is setso that it will penetrate into the ground to a predetermined level andthe transit movement of both the front and rear drive units 63 and 64 iscontrolled by the integrated drive and governor system described abovewith reference to FIG. 9. The integrated drive and governor system canbe used to move both the front and rear drive units 63 and 64 forwardly,while carrying the multi-purpose vehicle or tractor 62 upwardly off theground.

[0058] The milling or grinding drum 6 of the front drive unit 63 effectscutting and clearing of the vegetation. Fitting of an external mulchblower device 65 can further process the vegetation. Thus, the mulchedvegetation is removed by the blower device 65 after it has beenprocessed by the milling or grinding drum 6 by blowing it upwardly andrearwardly out of the front drive unit 63.

[0059] The forward-looking detector 10 of the front drive unit 63 isused to detect any buried objects larger than an anti-personnel mine.The information from the detector 10 and the ground speed radar 21, 22is processed by the on-board computer and global positioning system 26which is mounted on the multi-purpose vehicle or tractor 62.

[0060] When a large buried object is detected, the on-board computersends a signal to the flow control valve 55, thus stopping the forwardmotion of the whole apparatus. The global positioning system thenregisters the position co-ordinates of the detected object. The computeralso registers the size and shape of the object via information receivedfrom the detector 10 and the ground speed radar 21, 22. The operator ofthe multi-purpose vehicle or tractor 62 can then decide whether to carryon and grind up the detected object or to store the reference positionof the detected object and leave it for later removal.

[0061] The milling or grinding drum 6 of the rear drive unit 64 carriesout the destruction of any anti-personnel mines. The counter-rotation ofthe drum 6, relative to the direction of travel of the apparatus, causesa layer of soil to be lifted by the drum 6, together with any objectburied in this layer of soil. The depth of soil that the milling orgrinding drum 6 is allowed to penetrate determines the depth of thelayer of soil which is removed. The lifted soil and its contents arecarried to the top of the drum 6 where the action of the rotation of thedrum 6 and the tungsten carbide teeth 7 fixed to the drum 6 causes thesoil and its contents to be pulverised, comminuted and, possibly,detonated as it passes through the gap between the drum 6 and the shearbar 8.

[0062] The processed soil is then passed through the filtering device16, thus conditioning the soil. The soil can then be seeded andfertilised using an externally mounted seeding and fertilising machine66 mounted on the rear drive unit 64. The seed is then rolled in by thedrive roller 5 of the rear drive unit 64 and the mulch blown up over themulti-purpose vehicle or tractor 62 by the mulch blower 65 is able toland on top of the seeded ground and provide a suitable germinationcover.

[0063] As will be apparent from the above detailed description, thefront and rear drive units include a large number of common components,thereby minimising the number of replacement parts which have to be keptand facilitating regular maintenance and refurbishment operations.

1. A method for the clearance of anti-personnel mines, the methodcomprising: a) providing a first ground-engaging drive unit whichincludes a milling or grinding drum, b) providing a secondground-engaging drive unit which includes a milling or grinding drum, c)connecting the first drive unit to the front of a vehicle and the seconddrive unit to the rear of the vehicle to form a mine clearanceapparatus, and e) driving the mine clearance apparatus over the land tobe cleared in such manner that the milling or grinding drum of the firstdrive unit grinds up the surface vegetation and the milling or grindingdrum of the second drive unit grinds up a layer of soil and anyanti-personnel mines contained therein.
 2. Apparatus for use in theclearance of a minefield, the apparatus comprising first and secondground-engaging drive units each of which includes a milling or grindingdrum, and each drive unit being provided with connector means such thatthe first drive unit can be connected to the front of a vehicle and thesecond drive unit can be connected to the rear of the vehicle to form anapparatus which can be driven over the land to be cleared in such mannerthat the milling or grinding drum of the first drive unit grinds up thesurface vegetation and the milling or grinding drum of the second driveunit grinds up a layer of soil and any anti-personnel mines containedtherein.
 3. A method as claimed in claim 1 or apparatus as claimed inclaim 2, in which the vehicle is connected to the first and second driveunits in such manner that, when the apparatus is being driven over theland to be cleared of mines, the vehicle is supported clear of theground by said first and second drive units.
 4. A method as claimed inclaim 1 or apparatus as claimed in claim 2, in which the first driveunit includes a detector for the detection of buried objects larger thananti-personnel mines.
 5. A method as claimed in claim 1 or apparatus asclaimed in claim 2, in which the first drive unit includes blockageprevention means to prevent clogging of the milling or grinding drum dueto excessive vegetation, wet soil or other adverse conditions.
 6. Amethod as claimed in claim 1 or apparatus as claimed in claim 2, inwhich the first and second drive units each include a blast damagereduction device to obviate damage due to blast energy from explodinganti-personnel mines.
 7. A method as claimed in claim 1 or apparatus asclaimed in claim 2, in which the second drive unit includes a soilfiltering device for preparing the de-mined soil for agriculturalseeding.
 8. A method as claimed in claim 1 or apparatus as claimed inclaim 2, in which an integrated drive and governor system is providedfor moving the apparatus over the ground to be cleared under the powerof the prime mover of the vehicle.
 9. A method as claimed in claim 1 orapparatus as claimed in claim 2, in which an integrated steering andfixing system is provided for controlling movement of the apparatus overthe ground to be cleared under the power of the prime mover of thevehicle.
 10. A method as claimed in claim 1 or apparatus as claimed inclaim 2, in which means are provided on the first drive unit forprojecting ground-up vegetation upwardly and rearwardly so that it isapplied on top of ground-up soil discharged from the second drive unit.11. A drive unit which includes a milling or grinding drum, connectormeans for connection of the drive unit to the front or rear of a vehicleso that, when driven over the land to be cleared, the milling orgrinding drum grinds up either the surface vegetation or a layer of soiland any anti-personnel mines contained therein, and a blast damagereduction device to obviate damage due to blast energy from explodinganti-personnel mines.
 12. A drive unit as claimed in claim 11, whichincludes blockage prevention means to prevent clogging of the milling orgrinding drum due to excessive vegetation, wet soil or other adverseconditions.
 13. A drive unit as claimed in claim 11 or claim 12, whichincludes a detector for the detection of buried objects larger thananti-personnel mines.
 14. A drive unit as claimed in claim 11 or claim12, which includes a soil filtering device for preparing the de-minedsoil for agricultural seeding.